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Neptune’s Triton: A Moon Rich in Dry Ice and Carbon?

Published online by Cambridge University Press:  25 April 2016

A. J. R. Prentice
A. J. R. Prentice*
Affiliation:
Department of Mathematics, Monash University, Clayton, Victoria 3168
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Abstract

The encounter of the spacecraft Voyager 2 with Neptune and its large satellite Triton in August 1989 will provide a crucial test of ideas regarding the origin and chemical composition of the outer solar system. In this pre-encounter paper we quantify the possibility that Triton is a captured moon which, like Pluto and Charon, originally condensed as a major planetesimal within the gas ring that was shed by the contracting protosolar cloud at Neptune’s orbit. Ideas of supersonic convective turbulence are used to compute the gas pressure, temperature and rate of catalytic synthesis of CH4, CO2 and solid carbon within the protosolar cloud, assuming that all C is initially present as CO. The calculations lead to a unique composition for Triton, Pluto, and Charon: each body consists of, by mass, 18.5% solid CO2 ice, 4% graphite, 0.5% CH4 ice, 29% methanated water ice and 48% anhydrous rock. This mix has a density consistent with that of the Pluto-Charon system and yields a predicted mean density for Triton of 2.20±0.05 g cm−3, for satellite radius equal to 1750 km.

Type
Solar & Solar System
Information
Publications of the Astronomical Society of Australia , Volume 8 , Issue 4 , 1990 , pp. 364 - 367
Copyright
Copyright © Astronomical Society of Australia 1990

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